ProjectSummary/Abstract Respiratorysyncytialvirus(RSV)isaleadingcauseofsevereacutelowerrespiratorytractinfectionininfants andchildrenworldwide.BovineRSV(BRSV)iscloselyrelatedtohumanRSVandasignificantcauseof morbidityinyoungcattle.BRSVinfectionincalvesdisplaysmanystrikingsimilaritiestoHRSVinfectionin humans,andcattleareanoutbredpopulationthatisnaturallysusceptibletoBRSVinfection.Therefore,BRSV infectionincalvesrepresentsanexcellentmodelforstudyingRSVinfectionandantiviralimmunityinchildren. RSVispoorlyimmunogenicandthishasbeenacomplicatingfactorinthedevelopmentofasafeandeffective RSVvaccine.Polyanhydridenanovaccineshaveshowngreatpromiseasadjuvantsandvaccinedelivery vehiclesinrodentmodelsduetotheirabilitytopromoteenhancedimmunogenicitythroughboththerouteof administrationandtheabilitytoprovidesustainedantigenexposure.InapreviouslyfundedNIHgrant,the polyanhydridenanovaccineplatformwasusedtodevelopanefficacious,mucosalnanovaccinethat incorporatedthepost-fusionFandGproteinsfromBRSV.NeonatalcalvesvaccinatedwiththeBRSV-F/G nanovaccinedevelopvirus-specificcellularandhumoralimmuneresponsesinthemucosa,anddemonstrate significantreductionsinviralburdenanddisease-associatedpathology.Theoverallobjectiveofthisapplication istoimproveupontheestablishedefficacyofthepolyanhydridenanoparticleplatformforuseagainstRSV infectionintheneonate,andtofurthercharacterizethemucosalimmuneresponsesthatcorrelatewith resistancetoRSVinfection.TheexperimentsinAim1buildupontheestablishedefficacyofthepost-fusion F/Gnanovaccinewiththeincorporationofadditionaltolllikereceptoragonistsandmodificationstothe mucosal/parenteralinoculationregimen.TheexperimentsinAim2willdeterminetheefficacyofamucosal nanovaccinethatincorporatesthepre-fusionFandGproteinsfromBRSV,aswellascharacterizethe antibodyresponsetowardsthepre-fusionandpost-fusionFproteinintherespiratorytractofneonatalcalves. TheexperimentsinAim3willdeterminethedurationofimmunityinducedbypolyanhydridenanoparticle vaccination,whiledeterminingthemucosalimmuneresponsesthatcorrelatewithlong-termresistancetoRSV infectioninthecalf.MuchofourknowledgeofRSVinfectionandimmunitystemsfromstudiesinrodentsand adultanimals;?however,theexperimentsproposedherewillstudyanaturalhost-pathogeninteractionandwill examinetheresponseintheneonate,thesamepopulationcommonlyaffectedbysevereRSVdisease.We anticipatethatthesestudieswillhaveapositiveimpactbyidentifyingasafeandefficaciousvaccineforusein childrenandanimals,andbydeterminingtheimmuneresponsesthatarenecessaryforlong-termresistance againstRSVinfectionintheyoung.